(i) Field of the Invention
This invention relates to a toy device for simulating the action of a real mechanical digger.
(ii) Description of the Prior Art
Real mechanical diggers generally have four independent functions or movements including a primary boom which is pivoted at a lower end for raising and lowering, a secondary boom pivoted on the remote end of the primary boom so as to provide a knee action, a bucket mounted on the end of the secondary boom and pivotal through digging movement relative to the secondary boom. In addition the whole arm provided by the first and secondary booms and the bucket is pivotal about a vertical axis.
In commerical devices of this type, hydraulic power is used to drive the pivotal motion employing separate piston and cylinder units for lifting the primary boom, pivoting the secondary boom and pivoting the bucket.
Such an arrangement using hydraulic power is, however, totally unsatisfactory for toys in view of the cost and also in view of the safety factor. Various proposals have previously been made for mechanically actuated or lever actuated devices, but these have been severely limited and have not provided the four independent functions or movements which are necessary accurately to simulate the above mechanical digger.
Some such patented device is disclosed in U.S. Pat. No. 1,827,541 patented Oct. 13, 1931 to O. F. Opperman; in U.S. Pat. No. 2,247,619, patented July 1, 1941 by J. Penica and in U.S. Pat. No. 4,224,007, patented Sept. 23, 1980 by G. Chabot. Nevertheless, such toys did not accurately simulate the action of a real mechanical digger especially where such toy was to be used by children of different sizes and weights.